const harryPotter = 'Harry Potter'; 
let isBestseller = true;
const greatGatsby = "The Great Gatsby"; 
const smallValue = 0.0001;
let isModern = false;
const toKillMockingbird = 'To Kill a Mockingbird'; 
let preOrder = false;
let age = 18;
const book1984 = '1984'; 
let onDiscount = false;
let inStock = true;
const mobyDick = "Moby Dick"; 
const handmaidsTale = 'The Handmaid\'s Tale'; 
let negativeZero = -0;
let recommended = true;
const prideAndPrejudice = 'Pride and Prejudice'; 
let pinCode = '12345';
const oldManAndTheSea = "The Old Man and the Sea"; 
let negativeYear = -1925;
const yearOfPublication1 = 1925.5;
const beloved = "Beloved"; 
const catcherInRye = 'The Catcher in the Rye'; 
let isClassic = true;
let notYetDefined;
let outOfPrint = false;
let backInStock = true;
let isAvailable = null;